Discrete Envelope Tracking for Wideband RF Power Amplifiers
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Solution Overview
Problem
Envelope tracking power amplifiers face inefficiencies at lower signal levels and struggle with nonlinearities at higher signal levels, and are limited by channel width, making them unsuitable for wide channels and certain frequencies.
Innovation Solution
The implementation of enhanced level-based envelope tracking with two or more non-causal supply voltage levels and digital pre-distortion, which segments input signals into chunks and applies appropriate voltage levels based on signal characteristics to improve power efficiency and support wider channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If envelope tracking is used to improve power efficiency at lower signal levels, then power efficiency is improved, but the system becomes problematic across large channel widths and certain frequencies
Solution Approach 1:
The patent segments the continuous supply voltage into discrete levels (e.g., first supply level, second supply level, third supply level) that can be selectively applied based on signal characteristics. This segmentation allows the system to maintain power efficiency benefits while adapting to different channel widths and frequency ranges by choosing appropriate voltage levels for different operating conditions.
Solution Approach 2:
The system dynamically selects from multiple discrete supply voltage levels based on real-time signal envelope characteristics, channel width, and frequency conditions. This dynamic adaptation resolves the contradiction by enabling the power amplifier to optimize power efficiency across varying operating conditions including different channel widths and frequencies, rather than being limited to a single fixed envelope tracking approach.
2Device complexity
If fixed supply voltage is used to simplify the power amplifier design, then device complexity is reduced, but power efficiency deteriorates at lower signal levels
Solution Approach 1:
The patent changes the supply voltage parameter from a single fixed value to multiple discrete levels (first supply level, second supply level, third supply level). This parameter change enables the power amplifier to achieve better power efficiency at lower signal levels by selecting appropriate voltage levels, while maintaining relatively simple design through the use of discrete rather than continuous voltage control.
3Use of energy by moving object
If high supply voltage is used to improve efficiency at higher input values, then power efficiency is improved, but nonlinearities are introduced into the output signal
Solution Approach 1:
The system dynamically adjusts the supply voltage level based on the instantaneous signal envelope and operating conditions. By selecting from multiple discrete voltage levels rather than using a single high fixed voltage, the power amplifier can maintain efficiency at higher input values while avoiding the nonlinearities that would result from continuously varying the supply voltage, thus resolving the contradiction between efficiency and signal linearity.
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AI summary
An envelope tracking arrangement is disclosed and includes a level select component, a chunk supply component and a power amplifier. The level select component is configured to segment an input signal into chunks based on time and to select a chunk level for each chunk based on information or envelope information. The chunk supply component is configured to selectively provide a discrete supply voltage according to the selected chunk level. The power amplifier is configured to generate a radio frequency (RF) output signal based on the input signal and utilizing the discrete supply voltage.